That is serious hypocritical for the publisher to offer Mobi without DRM but a watermark and force people who read ePub to have to have DRM. But I suppose it's the only way to sell to a Kindle user without sending them to Amazon.

I'm pretty sure I bought watermarked epub and it was changed afterwards. I don't have it in my Digital Editions and I don't recall deleting it. Anyway there are many kindle users but not that many who read English in this country. This is a big company and they definitely have all the agreements sorted out to sell like they do.

Most of the books I buy from them are watermarked regardless of format.